ITHACA, N.Y. — With just one semester of school before X Prize qualification rounds begin, a flurry of work by different groups within the Cornell AXP team is progressing here simultaneously. We ordered supplies for transforming our Geo Metro into a plug-in hybrid electric vehicle after our last update, and with much of our hardware in house, we've begun work on the mule—and its modified drivetrain.

More From Popular Mechanics

The front-wheel drive 1991 Metro that we're testing for the competition is a small, fuel efficient vehicle, so a complete redesign of the drivetrain isn't necessary. Instead, we plan to tap into it's energy generation potential and supplement the combustion engine system to hit the magic 100-mpg number. Keeping the current drivetrain intact will also provide a fail-safe, should we find ourselves on the road without battery power or dealing with a motor malfunction.

We've also explored harnessing battery power around the alternator. But for efficiency's sake, we'd need to install a high-power alternator that could provide excess energy to the battery charger. While this could supply some power, a more efficient alternative might be to install an actual generator run by the Geo's engine. We haven't completely ruled any of these options out, but we still need to determine their feasibility. We'd like to harness as much power from the car as possible, so we're looking to develop a regenerative braking system, too.

The electric drivetrain's functionality starts with the National Instruments controller, which mimics many of the functions of the Metro's stock electronic control unit. It determines when to engage the motor (via a motor-dedicated controller) to draw energy from the batteries based on data including speed, engine output and braking. One advantage to this particular controller is that as engineering students, we're very familiar with MATLAB, a high-tech technical computing environment. And it works seamlessly with NI's LabVIEW programming platform.

Right now, we're aiming for 3-4 kWh of battery capacity for our Metro. We initially explored using lead acid, but lithium ion (which most electric vehicles will likely use in the future) is certainly not out of the question. The batteries will drive our 40-kWh Azure Dynamics AC 24 motor, which will power the rear wheels. Further testing will determine we will need additional batteries to hit 100 mpg and beyond.

We recently got a chance to take a peek at our competition at the AXP's official unveiling at the New York Auto Show. Over 60 teams have declared an intent to compete, and Cornell is one of only two from college. Obviously the AXP is our ultimate goal, but in the meantime we're working hard to complete enough of our mule to enter the upcoming Green Grand Prix in Watkins Glen, N.Y. Click here to follow our progress and to get information on how you, like PM, can support our work. —Richard Ma, CU AXP Publicity Lead